Liquid crystal display devices are widely used in displays for OA devices such as TVs and personal computers, and portable devices such as cellular phones and PDAs (Personal Digital Assistant).
Liquid crystal display panels generally have a structure in which a pair of transparent substrates are arranged opposing each other, with the edges thereof being bonded together with a sealing material. Liquid crystal is enclosed in the area sealed between the transparent substrates. One of the transparent substrates has a plurality of switching elements such as thin-film transistors (TFTs, hereinafter also referred to as “TFTs”) disposed for respective pixels in a matrix, and also a plurality of pixel electrodes each connected to a switching element. The other transparent substrate has an opposite electrode formed on the surface thereof. An electric field generated between the pixel electrodes and the opposite electrode changes the orientation state of the liquid crystal molecules, and changes the transmittance of the light entering the liquid crystal display panel to obtain desired display images in the liquid crystal display device.
The higher resolution of recent liquid crystal display panels has made it easier for a short circuit to occur between wiring and electrodes. Thus, it is essential to repair display anomalies caused by this short circuiting between the wiring and electrodes. If two adjacent pixel electrodes short circuit with each other, for example, then the two entire pixels that have short circuited will be bright spots or defects, resulting in a need to repair these display defects.
If pixel electrodes have short circuited with each other, then in general a laser is radiated from the rear side of the liquid crystal display panel to sever the short circuit defect portion, in order to repair the defect. However, if the short circuit defect has occurred in a location overlapping wiring and the like on the TFT substrate, then when the laser is used to sever the short circuit defect portion, the wiring of the TFT substrate will also be severed by the laser. When a wiring line is severed without an auxiliary wiring line for repairing disconnection, such as a storage capacitance wiring line, new defects will occur due to the wiring line being disconnected. Therefore, a short circuit defect repair method that radiates a laser to sever the short circuit defect portion is unable to be applied when the short circuit defect has occurred over the storage capacitance wiring line.
If, as described above, a short circuit defect between pixel electrodes occurs in an area overlapping the storage capacitance wiring line, then in general defect repair is performed by turning the two pixels that have the short circuit defect portion therebetween into dark spots. Specifically, as shown in FIG. 18, a drain wiring line 124DL connected to an upper electrode 124Cs of a storage capacitance element is severed (area LS in FIG. 18), and the upper electrode 124Cs and a lower electrode 122Cs are fused to connect with each other (shaded area M in FIG. 18), and the potential of a pixel electrode 127 is maintained at the storage capacitance potential. This makes the two short circuited pixel electrodes 127 visible as dark spots.
However, it is easily visible when two entire short circuited pixel electrodes are turned into dark spots, and the deterioration in display quality is noticeable even if repair of the short circuit defect is performed. There is also a set standard for how many pixels in one display panel can be dark spots, and the liquid crystal display panel will be considered defective if this set number is exceeded. Thus, there is also the risk of a reduction in yield if pixels are turned into dark spots in order to repair short circuit defects.
In Patent Document 1, an active matrix substrate is disclosed that has pixel electrodes divided into a plurality of small areas, and each small area is integrally connected via an electrical connection part. It is disclosed that if adjacent pixel electrodes on this active matrix substrate short circuit with each other at a location overlapping a light-shielding object such as a wiring line, then the electrical connection part is severed by radiating laser light onto the electrical connection part, which connects the small area that has the short circuit defect portion to the other small areas of the plurality of small areas that form a single pixel electrode. The small area with the short circuit defect portion is electrically separated from the other small areas in order to be able to repair the display defect without turning the entire two short circuited pixel electrodes into dark spots.